Did you know that mammals were saved by just the skin of their teeth almost 66 million years ago, in the Cretaceous period? Research shows that a prehistoric asteroid nearly decimated mammals along with dinosaurs.
The scene went something like this: "...an asteroid six miles in diameter crashed into what is now southeastern Mexico. The world went up in flames.Dinosaurs, along with the massive reptiles that ruled the sea and the sky, perished as forest fires raged across the globe, dust blotted out the sun, and Earth experienced intense heat, frigid cooling and then more heat."
It struck the earth with such mammoth force, that it destroyed about 93 percent of mammal species.
Scientists from the University of Bath discovered that the impact was massive. Earlier, it was surmised that the impact was not so severe as the rare species to be killed left behind small fossil records. The rare species would be most affected by the risk of extinction, according to Dr. Nick Longrich from the University of Bath. But today's fossil record is weighted in favour of species that survived through it.
Dr. Nick Longrich explained: "The species that are most vulnerable to extinction are the rare ones, and because they are rare, their fossils are less likely to be found. The species that tend to survive are more common, so we tend to find them."
It was also interesting that the asteroid's damage was reduced with the species recovering rapidly. In 300,000 years, the number of species on earth doubled in number, compared to the population that existed earlier than the mass extinction.
"It wasn't low extinction rates, but the ability to recover and adapt in the aftermath that led the mammals to take over," Longrich explains.
It also explains why the damage caused by the extinction event was underestimated by earlier scientists. Even as more fossils get included, the data examines more rare species that died out.
"Because mammals did so well after the extinction, we have tended to assume that it didn't hit them as hard. However, our analysis shows that the mammals were hit harder than most groups of animals, such as lizards, turtles, crocodilians, but they proved to be far more adaptable in the aftermath. It wasn't low extinction rates, but the ability to recover and adapt in the aftermath that led the mammals to take over," Longrich said.
Moreover, following the extinction, "there was an explosion of diversity" driven by evolutionary experiments in different parts of the world. As so many species evolved in different regions of the planet, "evolution was more likely to stumble across new evolutionary paths."
The study was published in the Journal of Evolutionary Biology.
